Method and system for aiming an rfid reader

ABSTRACT

A method and system for enhancing the accuracy of RFID tag reading is disclosed. An imaging device is used to facilitate aiming of the RFID tag in a manner that mitigates the likelihood of inadvertently reading a nearby RFID tag instead of the desired tag. In this manner, the utility of the RFID reader is substantially enhanced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/073,081, filed Mar. 4, 2005, which is incorporated herein byreference in its entirety for all purposes.

TECHNICAL FIELD

The present invention relates generally to radio frequencyidentification (RFID). The present invention relates more particularlyto a method and system for aiming an RFID reader in a manner thatenhances the likelihood of reading a desired RFID tag rather than anearby RFID tag.

BACKGROUND

RFID tags for identifying goods are well known. They can be applied toeither the goods themselves or to packaging for the goods. RFID tagstypically comprise an integrated circuit or chip and an antenna coupledto the chip. Information regarding the goods is stored upon the chip.For example, this information can include identification information,manufacturing information (such as what manufacturing processes havealready been performed and/or what manufacturing process is to beperformed next), customer information, or shipping information. RFIDtags can be formed upon labels to facilitate their application to thegoods or packaging.

The antenna typically comprises a plurality of conductive traces formedupon a substrate, such as the label. The antenna facilitatescommunication between the chip and an RFID reader and/or writer.Information is read from an RFID chip by first interrogating the chipwith a reader. The reader transmits a signal that is picked up by theantenna and is then communicated to the chip. The chip subsequentlyresponds by communicating a signal to the antenna that is thentransmitted to the RFID reader.

The information can be read by either a hand-held RFID reader or astationary RFID reader. Hand-held RFID readers can be used inwarehouses, for example. In a warehouse, an RFID reader can be used tolocate a desired item (having an RFID tag) from among many similaritems.

Stationary RFID readers can be used in manufacturing processes. Forexample, they can be used to determine what manufacturing process is tobe performed next on an item passing along a conveyor. Thus, an RFIDreader can be used to determine what color an item is to be painted orwhat accessories are to be added thereto. Such information can be usedto determine where in a manufacturing plant the item goes next and thusfacilitates automation of the manufacturing process.

One problem with contemporary RFID readers is that they tend to beundesirably indiscriminate with regard to which RFID tag is being read.Although they are somewhat directional with respect to how the beam istransmitted therefrom, they are not completely directional. Thetransmitted beam has some amount of spread and is thus capable ofreading other RFID tags that are proximate the desired RFID tag.Generally, if an RFID reader is pointed directly at the desired RFIDtag, it is much more likely to read only that particular RFID tag.However, if the RFID reader is slightly off (not well aimed), then itmay read a nearby RFID tag instead. Thus, it is sometimes difficult toknow which item's RFID tag is being read.

For example, if a person is looking for an item in a warehouse, the RFIDreader may indicate the presence of the desired item on a shelf.However, if there are other similar items nearby, then the user may havedifficulty determining which of the items is the desired one. As such,it is desirable to provide a way to better aim RFID readers or otherwisedetermine when they are pointed at a selected RFID tag.

BRIEF SUMMARY

Systems and methods are disclosed herein to provide an RFID reader thatis capable of enhanced discrimination among nearby RFID tags. Forexample, in accordance with an embodiment of the present invention, anRFID reader is combined with an imaging device. The imaging device isconfigured to facilitate aiming of the RFID reader such thatinadvertently obtaining readings from RFID tags other than the desiredRFID tag is less likely.

More specifically, in accordance with one embodiment of the presentinvention an RFID reader has a built-in imaging device and display. Thedisplay shows where the RFID reader is pointed, so that it can moreaccurately be pointed only at a desired RFID tag, while avoidingpointing it at other nearby RFID tags. This embodiment is well suitedfor hand-held use.

In accordance with another embodiment of the present invention, an RFIDreader is associated with an imaging device and machine vision is usedto determine when the RFID reader is aimed at a desired RFID tag. Inthis manner, manufacturing processes are enhanced. This embodiment iswell suited for stationary use.

This invention will be more fully understood in conjunction with thefollowing detailed description taken together with the followingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a semi-schematic side view of an exemplary hand-held RFIDreader, according to one embodiment of the present invention;

FIG. 2 is enlarged front view of the display of FIG. 1;

FIG. 3 is a block diagram of a representative manufacturing process thatuses a stationary RFID reader, according to another embodiment of thepresent invention; and

FIG. 4 is a flow chart showing the sequence of operation for themanufacturing process of FIG. 3.

Embodiments of the present invention and their advantages are bestunderstood by referring to the detailed description that follows. Itshould be appreciated that like reference numerals are used to identifylike elements illustrated in one or more of the figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One exemplary embodiment of the present invention is illustrated inFIGS. 1 and 2. This exemplary embodiment is a hand-held RFID readerassembly 20 that can be carried by a person and used to identify goodsand/or retrieve information relating to the goods. For example,hand-held RFID reader assembly 20 can be carried about a warehouse andused to locate goods that are to be shipped out.

With particular respect to FIG. 1, hand-held RFID reader assembly 20 cancomprise a reader 21 having a handle 23 extending downwardly therefrom.An imaging device 22 can be formed to reader 21 such it that imagesscenes in the direction that the hand-held RFID reader assembly 20 ispointing. A display 24 can be formed to the body such that it is readilyviewable by a person holding hand-held RFID reader 20.

Imaging device 22 can be an electronic imaging device, such as a CCDimager. Imaging device 22 provides an output to display 24. Imagingdevice 22 and display 24 cooperate to define an aiming device forhand-held RFID reader 20. Thus, by viewing display 24, a user candetermine what item reader 21 is pointed toward. It is the RFID tag ofthis item that reader 21 is most likely to read.

Imaging device 22 can alternatively be an all-optical (non-electronic)imaging device. For example, imaging device 22 can be similar to anoptical viewfinder device of a film camera.

With particular reference to FIG. 2, display 24 optionally comprisesindicia formed thereon to facilitate more accurate aiming of reader 21.For example, display 24 can comprise crosshairs 25 and/or circular bullseye target which is comprised of concentric circles 26 and 27.

Optionally, the indicia can comprise a gradient, such that display 24becomes either lighter or darker from the center to the outer edgesthereof. For example, a dark dot can be formed at the center of thedisplay (such as between cross hairs 25). The dot can define the centerof a gradient that becomes lighter as the gradient is further from thedot.

In each instance, the indicia are used to aim hand-held RFID readerassembly 20 by helping the user to center the desired RFID tag to beread in display 24. Thus, cross-hairs 25 may be placed over the RFID tagand/or the RFID tag may be positioned within inner circle 27. Suchaiming of reader 21 helps to assure that hand-held RFID reader assembly20 is pointed at the desired item and thus tends to mitigate thelikelihood of obtaining a reading from a nearby RFID tag.

Optionally, a range finder 28 (FIG. 1) can be used to determine therange from imaging device 22 to the RFID tag to be read. Range finder 28facilitates the use of indicia that better indicate the likelihood thata desired RFID tag will be read and that nearby RFID tags will not beread. For example, range finder 28 can be configured to cooperate withdisplay 24 such that indicia formed thereon delineate a predeterminedthreshold of the output power of the excitation beam of RFID reader 21.

Range finder 28 can be an active range finder, such as an ultrasonicrange finder, a microwave range finder, or a laser range finder.Alternatively, range finder 28 can be a passive range finder such as asplit view range finder. Such passive range finders are particularlysuitable for use with all-optical imaging devices.

More particularly, range finder 28 can cooperate with display 24 toposition cross-hairs 25, one of the circles 26 or 27, and/or a desiredportion of a gradient at the 3 dB power boundary of a cross-section theexcitation beam of RFID reader 21 in the plane of the image (in the areaof the RFID tag). That is, display 24 can provide a visualrepresentation of the power of the excitation beam of RFID reader 22.

For example, inner ring 26 can represent the 3 dB boundary. Inner ring26 would then vary in size as the distance between imaging device 22 andthe RFID tag changes, to reflect the changing size of the 3 dB boundary.An RFID tag within this boundary is much more likely to be read than anRFID tag outside of this boundary. Thus, in use the goal is to aim theRFID reader assembly 20 such that the desired RFID tag is within theboundary and all other RFID tags are outside of the boundary.

It is worthwhile to appreciate that the use of a 3 dB power boundary isby way of example only, and not by way of limitation. Other power ornon-power boundaries may similarly be used. The level and/or pattern ofthe particular boundary used may be based upon the readability of a tag.The readability of a tag can depend upon the type of tag. For example,different types of tags typically have different antennas that canaffect the readability thereof. Optionally, the user can select thelevel and/or pattern of the boundary to be displayed, such as byselecting the type of tag to be read.

Referring now to FIG. 3, another exemplary embodiment of the presentinvention is shown. In this exemplary embodiment, a stationary RFIDreader assembly 50 is configured for stationary use, such as in anassembly or test line. Stationary RFID reader assembly 50 comprises areader 46 having an imaging device 47 formed thereto. However, imagingdevice 47 can alternatively be separate from reader 46. Indeed, imagingdevice 47 can be disposed away from reader 46. For example, imagingdevice 47 can be several inches, or even several feet, away from reader46. Imaging device 47 can generally be located anywhere that facilitatesimaging of the RFID tags in a manner that enhances the ability of reader46 to discriminate among adjacent RFID tags.

In this instance, stationary RFID reader assembly 50 is used in amanufacturing process to test RFID tags after bar codes have beenprinted onto labels that contain the RFID tags. Optionally, a bar codereader 42 can similarly be used to verify the printing process bychecking the bar codes that were printed upon the labels. The use ofimaging device 46 assures that both the proper RFID tag and the properbar code are being read.

According to this exemplary manufacturing process, a printer/RFID writer41 prints bar codes upon label stock 45 from supply reel 44. The printedlabels are then wound onto take-up reel 48. Label stock 45 comprises aplurality of labels. Each label comprises an RFID tag. One or more barcodes can be printed upon each label. The labels can be placed upon thepackages of goods that are to be shipped from a warehouse. For example,the RFID tag can contain a unique serial number, a product or modelnumber, information regarding the product (such as its size, color, andincluded options), and an address to which it is to be shipped. The barcode(s), if used, can contain similar, though typically less,information. Alpha-numeric information (text) of at least an address canalso be printed upon the label.

It is important to verify the accuracy and integrity of the RFID tagsand/or the bar codes. The RFID tags and/or the bar codes are frequentlyused to route the package to its intended recipient. Thus, verifying theaccuracy and integrity of the RFID tag and/or the bar codes can assure,among other things, that the printer/RFID writer 41 is functioningproperly and that the package is likely to arrive at the intendedlocation.

A printer/RFID writer 41 prints the bar codes upon the labels andprograms the RFID tags. More particularly, a print head 43 ofprinter/RFID writer 41 prints the bar codes and any alpha-numericinformation, while an RFID writer 40 writes the desired information tothe RFID tag of the label.

Bar code reader 42 verifies the accuracy and integrity of bar codesprinted upon the labels. Similarly, RFID reader 46 verifies the accuracyand integrity of RFID tags associated with the labels.

When verifying the accuracy and integrity of the bar codes and RFIDtags, it is important to know which bar codes/RFID tags are beingchecked. Because the individual labels are close to one another on thelabel stock, it is possible to make mistakes regarding which labels arebeing read. This is particularly true for the RFID tags, since RFIDreader 46 will typically be less directional than bar code reader 42.

Imaging device 47 images the labels that pass from supply reel 44 totake-up reel 48. A signal representative of the images made by imagingdevice 47 can be provided to machine vision controller 49. Machinevision controller 49 can be configured to recognize when a label isdisposed beneath RFID reader 46 in a manner that mitigates thelikelihood of inadvertently reading the RFID tag of an adjacent label.

Thus, machine vision controller 49 can determine when RFID reader 46 isto read a label. Machine vision controller 49 thus can provide a signalto RFID reader 46 that determines when RFID reader is to read an RFIDtag. Similarly, machine vision controller 49 can provide a signal to barcode reader 42 that determines when bar code reader 42 is to read a barcode. Optionally, machine vision controller 49 can provide a controlsignal to a drive controller 48 of printer/RFID/ writer 41 so as tocontrol the movement of label stock 45 with respect to bar code reader42 and/or RFID reader 46. Thus, according to one or more aspects of thepresent invention a way is provided for determining when an RFID readeris pointed toward a selected RFID tag, so as to mitigate the likelihoodof inadvertently reading a wrong RFID tag.

Generally, a range finder is not needed in such industrial processapplications because the distance between RFID reader 46 and the RFIDtags is usually fixed. However, in applications where this distance isnot fixed, a range finder may cooperate with machine vision controllerto assure that the desired RFID tag is within a predetermined boundary,as discussed above. For example, a range finder may be used whenscanning different sized boxes as they move on a conveyer belt, sincethe different sizes can define different ranges.

Embodiments described above illustrate, but do not limit, the invention.It should also be understood that numerous modifications and variationsare possible in accordance with the principles of the present invention.Accordingly, the scope of the invention is defined only by the followingclaims.

1-26. (canceled)
 27. A method for making an RFID reader assembly, themethod comprising: providing an RFID reader; providing an imagingdevice; attaching the imaging device to the RFID reader, wherein theimaging device is configured to scan an image of an RFID tag; coupling avision controller to the imaging device, wherein the vision controlleris configured to send a signal, based on a signal received from theimaging device, to the RFID reader when the selected RFID tag is to beread; and providing a drive controller coupled to the vision controller,wherein the vision controller is configured to send a second signal,based on a signal from the imaging device, to the drive controller tocontrol the movement of the RFID tag.
 28. The method as recited in claim27, further comprising attaching a display to the RFID reader, thedisplay being configured to show an image from the imaging device. 29.The method as recited in claim 27, further comprising attaching a rangefinder to the RFID reader, the range finder being configured tofacilitate the definition of a boundary that can be shown upon thedisplay device. 30-36. (canceled)
 37. The method of claim 27, furthercomprising providing a bar code reader, wherein the vision controller isconfigured to send a signal, based on a signal from the imaging device,to the bar code reader when a bar code is to be read.
 38. (canceled)